A flange is generally welded along the circumference of the end of a pipe to connect pipes, valves and shafts together.
FIG. 1 is an exploded perspective view showing a conventional flange. As shown FIG. 1, the conventional flanges 100 and 200 are welded on the ends of pipes 300 that face one another. A plurality of holes 110 and 210 is formed to receive bolts 120 on the conventional flanges 100 and 200 to be near to the edge of the conventional flanges 100 and 200 at regular intervals. Therefore, the pipes 300 are connected through fastening the two flanges 100 and 200 by tightening the bolts 120 and the nuts 220 through the holes 110 and 210.
As described above, the conventional flanges 100 and 200 includes holes 110 and 210 formed to be near to the edge thereof for receiving the bolts and the nuts. The conventional flanges 100 and 200 are jointed tighter by tightening the bolts 120 and the nuts 220 through the holes 110 and 210 so as to connect the two pipes. The tightly sealed conventional flanges 100 and 200 prevent the connected pipes from being leaked although a predetermined pressure is created in the connected pipes.
That is, the conventional flanges 100 and 200 must be formed to have a wide edge to form holes 110 and 210 to receive the bolts 120 and the nuts 220. Therefore, the flanges 100 and 200 must be manufactured larger to include the wider edges and it increases the manufacturing cost thereof.